MUTATION - -(MA); deletion of ~22 kb involving both alpha genes (see Fig. 24)
 
AMINO ACID REPLACEMENT None
TYPE OF ALPHA-THAL alpha-Thal-1 [- -/]
MECHANISM The deletion involves both alpha-globin genes; absence of functional alpha-mRNAs
IDENTIFICATION Gene mapping; see diagram below
Positions of the restriction sites and the sizes of the fragments for several enzymes for a chromosome with a zeta-globin gene triplication. The extent of the deletion is shown at the bottom (black bar), with the limits of the breakpoints indicated by white bars.[Figure not yet available on-line.]
HEMATOLOGY IN HETEROZYGOTE(S) Hb 12-13 g/dl; MCV 70-72 fl; MCH 23-35 pg; alpha/beta ratio 0.6-0.7
HEMATOLOGY IN HOMOZYGOTE(S) None
OCCURRENCE In a few Spanish families
HAPLOTYPE Not determined
FOUND IN COMBINATION WITH ABNORMAL HB(S) Not reported
FOUND IN COMBINATION With the -alpha(3.7 kb) deletion causing Hb H disease: Hb 10-11 g/dl; MCV 70-72 fl; MCH 20-22 pg; Hb A2 0.8%; Hb H 5-7%; inclusion bodies present; alpha/beta ratio 0.4-0.5
OTHER INFORMATION Deletion is associated with a zeta-globin gene triplication
       
REFERENCES
1. Gonzalez-Redondo, J.M., Gilsanz, F., and Ricard, P.: Hemoglobin, 13:103, 1989.
2. Villegas, A., Sánchez, J., Carreño, D.L., Ropero, P., González, F.A., Espinós, D., Peñalver, M.A., and Lozano, M.: Am. J. Hematol., 49:294, 1995.


This material is from the book A Syllabus of Thalassemia Mutations (1997) by Titus H.J. Huisman, Marianne F.H. Carver, and Erol Baysal, published by The Sickle Cell Anemia Foundation in Augusta, GA, USA. Copyright © 1997 by Titus H.J. Huisman. All rights reserved. Neither this work nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, microfilming and recording, or by any information storage and retrieval systems, without permission in writing from the Author.